Here, the various ways of visualzing the data generated by the simulations or to obtain certain data from the simulations are explained.

Writing output

Silo and VTK output

TODO

Binary output

Afivo-streamer allows a simulation to be continued at a later time through the use of binary output files (DAT files). To do this, the simulation is initially run and set up to write DAT files, which could be achieved by using the following flags:

• datfilewrite - set to true if you want to write DAT files
• datfileper_outputs - control when DAT files are written by equating this to an integer (e.g. datfileper_outputs = 20 means that a DAT file is created every after 20 output files are written)

The created DAT files would have the same name as the SILO files written by the program. To begin another simulation run from a particular DAT file, set the flag restart_from_file equal to a string with the name (and location, if in a different directory) of the DAT file you want to use as the starting point of the other simulation run.

The log file

TODO

2D planes

TODO

1D lines

TODO

Making videos using VisIt

• The following link gives an overview on creating movies in VisIt: Making movies in VisIt.
• To add/customize the appearance of stuff like legends, titles, time progress bar, go to Controls -> Annotation on the VisIt menu.

Issues encountered and the solutions:

• Waiting message: While making the videos using the default options, users may encounter a window saying 'VisIt is waiting for a CLI to launch on localhost'. This is due to the missing xterm package on the system. It can be installed using sudo dnf install xterm(Fedora) or sudo apt-get install xterm (Ubuntu).
• Weird video generated: The videos generated sometimes have a different color scheme or maybe the frames are inverted/mirrored. This was solved by installing the ffmpeg package using sudo dnf install ffmpeg (Fedora) or sudo apt-get install ffmpeg (Ubuntu).`

• Bad video quality/Custom videos: The videos generated by VisIt maybe of bad quality or the user may want to make videos of a particular portion of the simulation domain. Then a set of PNG/JPEG images can be generated using VisIt, which can be suitably modified and made into a video using ffmpeg as follows:

  Suppose the set of PNG files are movie0000.png ... movie0032.png and the output video name is resultVideo.mp4, then the necessary command is

  ffmpeg -i movie%04d.png resultVideo.mp4